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Plastic debris gathered from the ocean. Photo courtesy of NOAA.

Building a library of microplastics in the Salish Sea

August 28, 2018

By Shannon Black

Microplastics are found throughout the Salish Sea, but “surprisingly little is known about the sources of these particles,” report Canadian scientists who presented their findings last spring at the Salish Sea Ecosystem Conference in Seattle. Now the group, led by Dr. Peter Ross at the Vancouver Aquarium is working to categorize the types of microplastics being found in the world’s oceans with the hope of identifying their origins and stopping the problem at its source.

The team is using Fourier Transform Infra Red spectrometry (FTIR) to create an imaging database of confirmed particles. Much of what the team has found so far in British Columbia — roughly 75% of it — includes plastic microfibers that are in especially high concentrations in waters near urban centers. Scientists suspect these fibers are coming from sources such as synthetic sweaters and other clothing that shed microplastics when they are washed. The water then passes through wastewater treatment plants directly into the Salish Sea.

Microplastics are defined as plastic particles less than 5 millimeters in size and vary in shape, color, chemical composition, and density. Manufactured plastics fall under the category of primary microplastics, which include nurdles and microbeads. Nurdles are small plastic pellets approximately the same size as a lentil, mass quantities of which are melted to form nearly all macroplastics. Annually the United States manufactures approximately 60 billion pounds of nurdles. Microbeads can be found in some exfoliates and even toothpastes, however, they were nationally banned in 2015 as part of the Microbead-Free Water Act. Secondary microplastics are the byproduct of larger pieces of plastic that have been fragmented through the processes of photodegradation and/or mechanical weathering. These processes are made more extreme when plastics end up in the oceans where shade is nonexistent, solar radiation is inescapable and the physical forces of waves are continuous.

While the health impacts of microplastics are not yet well understood, Ross says the particles are of special concern because they are regularly ingested by invertebrates like shellfish as well as zooplankton at the bottom of the food chain. “We’re encountering a pollutant unlike any pollutant we’ve ever seen before,” Ross told the CBC.

This story was produced as part of the Puget Sound Institute’s coverage of findings presented at the 2018 Salish Sea Ecosystem Conference in Seattle. Read more stories from the series on the Encyclopedia of Puget Sound.